Deep mineralization of hypersaline wastewater for resource recovery via a MXene-doped Ti4O7 flow-through electrode.

Efficient removal of organic pollutants from hypersaline wastewater is critical yet challenging for resource recovery. Here, a MXene-doped Ti₄O₇ (Ti₃C₂/Ti₄O₇) flow-through anode achieved an outstanding 90.4% dissolved organic carbon (DOC) removal from real waste brines, nearly doubling the performance of a conventional pristine flow-by configuration (49.1%). Notably, this heterostructure enhanced hydroxyl radical (•OH) generation by 3.52-fold. Scavenging kinetics revealed that the system reconfigured the reactive matrix, establishing •OH (66.7%) and direct electron transfer (DET, 31.9%) as the dominant mechanisms while minimizing reactive chlorine species (RCS) interference. FT-ICR MS and linkage analysis identified dealkylation and oxygenation as the prevailing transformation pathways. The elevated •OH concentration effectively intercepted chlorinated intermediates via secondary oxidation, reducing adsorbable organic chlorine (AOCl) accumulation by 19.8% and slashing effluent bioluminescence inhibition from 76.5% to 21.6%. Frequency-based paired mass distance (F-PMD) analysis coupled with machine learning demonstrated that this radical intensification shifted the organic degradation mechanism from chemical structural selectivity to physical mass-transfer control. Consequently, the recovered NaCl transformed from yellow aggregates into pristine white crystals, with its carbon mass fraction decreased from 17.15% to 0.68%. Overall, this study presents an intensified electrochemical flow-through technology that achieves deep brine mineralization, providing a highly efficient strategy for high-value resource recovery.